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FXUS61 KBUF 220553
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
153 AM EDT Mon Apr 22 2024

.SYNOPSIS...
High pressure nosing northeast from the Ohio valley will supply us
with a nice start to the work week...guaranteeing ample sunshine
with the mercury rebounding some 5 to degrees higher than those from
Sunday. The fair dry weather will last through at least the first
half of Tuesday...then a slow moving cold front will produce
widespread rain showers Tuesday night into Wednesday morning. Dry
weather will then return for Thursday and Friday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A moisture starved cold front will cross the area tonight bringing
one last shot of cooler air that will keep temperatures below normal
through the start of the new work week. Other than a few light rain
showers for the Eastern Lake Ontario region overnight, high pressure
builds across the region providing dry weather and lighter winds for
through Monday. Chilly night on tap with mid and upper 20s higher
terrain and low to mid 30s elsewhere. As mentioned, temperatures
will remain below average for Monday, however airmass will modify
some. This will yield highs ranging from the mid and upper 40s
across the higher terrain, to the low and mid 50s elsewhere.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
Main focus this period continues to be on the next round of
widespread soggy weather followed by a sharp cooldown around the
midweek timeframe.

High pressure will slowly shrink off the East Coast Monday night
through Tuesday. This will maintain dry and relatively milder
weather to start the period as warmer air advects into the region on
the backside of the high. Lows Monday night will range from the low
40s across far western NY to the mid/low 30s across the North
Country. As the area sits firmly within the next incoming system`s
warm sector, highs Tuesday should top out in the low to mid 60s. A
50kt 850H jet embedded within the WAA regime will likely lead to a
breezy day northeast of Lake Erie, with gusts of 30-35mph expected.

This system will come in the form of a robust mid-level shortwave
sliding east across the Great Lakes Tuesday. As it trudges eastward,
this shortwave is expected to partially phase with a deeper closed
low wobbling along the eastern shores of Hudson Bay, as well as a
weaker shortwave moving across the Mississippi Valley. This will
create a deeper longwave troughing pattern that will dig across the
Northeast through Wednesday before shifting to the Canadian
Maritimes by late Wednesday night. Several waves of surface low
pressure are expected to form ahead of the primary mid-level trough
axis, with broad-scale cyclogenesis allowing the system to tap into
a reservoir of GOMEX based moisture. While a few showers or a stray
thunderstorm could reach far western NY late Tuesday
afternoon/evening, a swath of soaking rain will move through the
region Tuesday night courtesy of broad scale ascent under the
poleward exit region of a 110kt upper level jet. Little to no
hydrological concerns at this juncture given the dry conditions
earlier in the week...Basin averaged QPF amounts through Wednesday
morning will average 0.25-0.5" in most areas, a bit higher at 0.5-
0.75" east of the lakes.

The system`s main cold front will begin to plow through the region
behind the rain Wednesday morning. Mid-range guidance is starting to
come into better agreement on the progression of this front and how
much cold air spills into the region behind it. Due to discrepancies
on the amount of phasing between the shortwave over the Great Lakes
and the low near Hudson Bay, previous runs of the GFS were
significantly colder (850H temps bottoming out around -12C) than the
deterministic CMCNH/ECMWF and their respective ensembles (closer to -
2C). While there remains uncertainty in the timing and true depth of
the cold airmass, the trend among the latest guidance has been
somewhere in the middle of these solutions, with the overall
consensus leaning colder. Should these trends hold, this will
support a strong non-diurnal temperature curve with the front
Wednesday, with temps sharply falling across the region from the 40s
early in the morning well into the 30s through the remainder of the
day. While temps at the sfc and aloft will support at least a
partial changeover to wet snow, this colder airmass also looks to be
quite a bit drier with most of the region precip-free by the
afternoon. This, combined with the strong late April sun angle,
should greatly minimize the threat of snow sticking anywhere other
than the highest hilltops south of Buffalo and east of Lake Ontario.

Within the post-frontal airmass and under mostly clear skies,
Wednesday night is expected to be downright cold. Lows will likely
be sub-freezing across the entire region, through bottoming out in
the low 20s across the higher terrain of the Southern Tier and North
Country.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
A large Canadian sfc high along with increased ridging will provide
dry weather for Thursday and most of Friday. The sfc high will
center over the forecast area by Thursday night and track to the New
England coast by Saturday morning.

A weakening trough and sfc low will track across the plains on
Friday and center over the Great Lakes on Saturday night. This will
result in increasing rain potential starting later Friday
evening/overnight as the warm front out ahead of the system
approaches/crosses the region. Showers and periods of steadier rain
will continue through much of Saturday as a plume of GOMEX moisture
pushes north across the Ohio Valley. With the warm sector of the
system over the region, there will be the chance for some
thunderstorms on Saturday, with the best chance for some storms over
the southwestern portions of the area. Still some uncertainty as far
as shower/rain amount goes among guidance with the GFS keeping the
sfc low track closer to the forecast area and keeping the trough a
bit stronger as well. Other forecast models limit the moisture
influx and pull the sfc low farther north, resulting in less precip
overall. Showers should continue into Sunday with more breaks,
especially into the afternoon.

Temperatures during the period will be below normal to start with
warming each day to above normal by the weekend.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
VFR conditions will be in place through the TAF period.

Outlook...

Monday night...VFR.
Tuesday...Mainly VFR. A chance of showers later in the afternoon.
Tuesday night and Wednesday...Areas of MVFR with showers.
Thursday and Friday...Mainly VFR.

&&

.MARINE...
High pressure nosing into the region from the Ohio valley will allow
winds and waves to subside a bit through daybreak...then to remain
below small craft advisory criteria through Monday night.

Southerly winds will become southwesterly and freshen Tuesday and
will likely result in Small Craft Advisory conditions into midweek.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...None.

&&

$$

SYNOPSIS...RSH
NEAR TERM...AR/JM
SHORT TERM...PP
LONG TERM...SW
AVIATION...RSH
MARINE...JM/RSH